Brake head-centering device for railway brake apparatus

ABSTRACT

The disclosure concerns brake apparatus for railway cars and locomotives in which the brake head is journaled on a pivoting hanger and is centered by a biasing spring. A four-bar parallelogram linkage orients the seat of the biasing spring with respect to a portion of the vehicle so as to maintain alignment of the head relative to the braking surface of the wheel during pivotal movement of the hanger.

United States Patent [1 1 Mcllroy 1 BRAKE HEAD-CENTERINC DEVICE FOR RAILWAY BRAKE APPARATUS [75] Inventor: Jack E. Mcllroy, Le Ray, NY.

[73] Assignee: General Signal Corporation, New

York, N.Y.

[22] Filed: Dec. 14, 1971 [21] Appl. No.: 207,774

[52] US. Cl. 188/212, 188/221.1 [51] Int. Cl. Fl6d 65/06 [58] Field of Search [88/207, 209, 212,

[56] References Cited UNITED STATES PATENTS 1,456,632 5/1923 Elliott; 188/212 X |4s| July 3,1973

7/1932 Busch 188/212 X 8/1949 Barrows 188/212 X Primary ExaminerDuane A. Reger Attorney-George Vande Sande, Harold S. Wynn et a1.

[ 5 7 ABSTRACT The disclosure concerns brake apparatus for railway cars and locomotives in which the brake head is journaled on a pivoting hanger and is centered by a biasing spring. A four-bar parallelogram linkage orients the seat of the biasing spring with respect to a portion of the vehicle so as to maintain alignment of the head relative to the braking surface of the wheel during pivotal movement of the hanger.

5 Claims, 3 Drawing Figures PATENTED JUL 3 I975 FIG.3

FIG.2

FIG]

BRAKE IIEAD-CENTERING DEVICE FOR RAILWAY BRAKE APPARATUS BACKGROUND AND SUMMARY OF THE INVENTION U.S. Pat. application Ser. No. 113,280, filed Feb. 8, 1971, discloses a brake head-centering device for use on railway cars and locomotives in which the brake head is equipped with a biasing spring which orients it with respect to a seat journaled on a pivot carried by the hanger, and with a four-bar parallelogram linkage which maintains a prescribed orientation of that seat relative to the hanger actuator. The orientation of the hanger actuator with respect to the horizontal varies only slightly during pivotal movement of the hanger; therefore, proper orientation of the seat relative to the actuator produces the desired result of maintaining alignment of the brake shoe with respect to the wheel. Although this device performs satisfactorily, it is inconvenient to use it in installations where space considerations dictate that the hanger pass between the two support ears of the brake head. Moreover, since one link of the parallelogram linkage is attached to the hanger actuator, which normally is a hydraulic cylinder, this scheme makes maintenance of the cylinder more inconvenient than is desirable.

The object of this invention is to provide an improved brake head-centering device of the type under discussion which is more convenient to use than the one described in the above identified application. According to this invention, the orientation of the seat for the head-biasing spring is controlled by a four-bar parallelogram linkage whose fixed or reference link is a portion of the vehicle itself, rather than a portion of the hanger actuator as in the earlier design. This difference facilitates incorporation of the head-centering scheme in cases where the hanger passes between the head ears, and, since the four-bar linkage has no connection to the actuator, servicing of the actuator requires removal of only a single bolt.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is described herein in detail with reference to the accompanying drawings in which:

FIG. 1 is an elevation view of the improved centering device incorporated in a typical disc brake unit.

FIGS. 2 and 3 are sectional views taken, respectively, on lines 2-2 and 3-3 of FIG. 1.

DESCRIPTION OF ILLUSTRATED EMBODIMENT The illustrated disc brake unit 11 is one of a pair of similar units associated with the two wheels on a car axle and which are actuated by a common hydraulic cylinder 12 which is suspended between the units and is parallel with the axle. Each unit 11 comprises a twopiece hanger 13 which depends from a pivot bolt 14 journaled in a bracket 15 attached to the car body or the truck frame and has a bifurcated lower end whose spaced portions 16 and 17 are bridged by a second pivot bolt 18 to which either the rod or the cylinder element of brake cylinder 12'is attached. The shank portion 19 of hanger 13 is positioned between the integral supporting cars 21 and 22 of a brake head 23 and carries a third bolt 24 which serves as the pivot for the which is engaged by an intermediate portion of a leaf spring 27 which is held captive by a pair of pins 28 projecting from supporting car 21. Spring 27 tends to assume the illustrated null position in which it lies flat against surface 26, and consequently it biases head 23 about pivot 24 to a prescribed angular position with respect to cam member 25. The spring is stiff enough to hold the head in this position under service conditions whenever the brakes are released, but not so stiff as to preclude the head motion required during a brake application to maintain the block type shoe elements 29 in flat engagement with the brake plate 31.

The cam member 25 is joined to bracket 15 by an articulated link 32 whose opposite ends are journaled on pins 33 and 34. As shown in FIG. 1, the axes of these pins and of pivots l4 and 24 are located at the corners of a four-bar parallelogram A-B-C-D composed of portions of hanger 13, bracket 15, cam member 25 and link 32. This four-bar linkage inherently maintains parallelism between bars B and D during pivotal movement of hanger 13, and therefore fixes the orientation of cam surface 26 relative to bracket 15. Since the bracket is attached to a portion of the car, its orientation with respect to the horizontal changes very little during service. Therefore, since spring 27 fixes the orientation of head 23 relative to surface 26 when the brakes are released, it follows that the angular position of the head in space under release conditions will remain fixed. Thus, if the inclination of surface 26 with 'respect to the vertical is selected initially to provide alignment between blocks 29 and brake plate 31, this alignment will be maintained during service regardless of the fact that the angular position of hanger 13 under release conditions changes as slack is taken up.

While the invention has been described in connection with a disc brake unit, it should be understood that, as in the case of the apparatus of application Ser. No. 113,280, it may also be incorporated in a tread brake unit.

I claim:

1. A brake-head-centering device for railway brakes having a brake head suspended from a portion of a vehicle and apparatus for selectively applying braking torque through the brake head to the vehicle wherein the improvement comprises;

a. a hanger pivoted at its upper end to the portion of the vehicle for suspending the brake head,

b. a centering cam for centering the brake head,

c. means for pivoting the brake head and the centering cam at an intermediate point in the hanger, and

d. linkage means laterally disposed relative to the hanger having pivot points connecting a portion of the vehicle and a point of the cam spaced from said intermediate point for maintaining the cam and the brake head in substantially the same plane as the hanger is actuated about the pivot at its upper end.

2. A brake head-centering device for railway brakes according to claim 1 wherein the brake head has a leaf spring bearing against the cam for maintaining the brake head in alignment with the cam.

3. A brake head-centering device for railway brakes according to claim 2 wherein the leaf spring is suspended between anchor points at its ends and an intermediate point in the spring bears against the cam.

4. A brake head-centering device for railway brakes according to claim 3 wherein the cam extends between one end of the linkage and the leaf spring and its connection to the hanger is at an intermediate point.

5. A brake head-centering device for railway brakes according to claim 1 wherein a parallelogram is formed by connecting the pivot points of the hander, cam and linkage.

11K I1! 1k 

1. A brake-head-centering device for railway brakes having a brake head suspended from a portion of a vehicle and apparatus for selectively applying braking torque through the brake head to the vehicle wherein the improvement comprises; a. a hanger pivoted at its upper end to the portion of the vehicle for suspending the brake head, b. a centering cam for centering the brake head, c. means for pivoting the brake head and the centering cam at an intermediate point in the hanger, and d. linkage means laterally disposed relative to the hanger having pivot points connecting a portion of the vehicle and a point of the cam spaced from said intermediate point for maintaining the cam and the brake head in substantially the same plane as the hanger is actuated about the pivot at its upper end.
 2. A brake head-centering device for railway brakes according to claim 1 wherein the brake head has a leaf spring bearing against the cam for maintaining the brake head in alignment with the cam.
 3. A brake head-centering device for railway brakes according to claim 2 wherein the leaf spring is suspended between anchor points at its ends and an intermediate point in the spring bears against the cam.
 4. A brake head-centering device for railway brakes according to claim 3 wherein the cam extends between one end of the linkage and the leaf spring and its connection to the hanger is at an intermediate point.
 5. A brake head-centering device for railway brakes according to claim 1 wherein a parallelogram is formed by connecting the pivot points of the hanger, cam and linkage. 